Acalculia
Encyclopedia
Acalculia is an acquired impairment
in which patients have difficulty performing simple mathematical tasks, such as adding, subtracting, multiplying and even simply stating which of two number
s is larger. Acalculia is distinguished from dyscalculia in that acalculia is acquired late in life due to neurological injury such as stroke
, while dyscalculia is a specific developmental disorder
first observed during the acquisition of mathematical knowledge. The name comes from the Greek
"a" meaning "not" and Latin
"calculare", which means "to count".
(especially the angular gyrus
) and the frontal lobe
and can be an early sign of dementia
. Acalculia is sometimes observed as a "pure" deficit, but is commonly observed as one of a constellation of symptoms, including agraphia, finger agnosia and left-right confusion, after damage to the left angular gyrus, known as Gerstmann's syndrome (Gerstmann, 1940; Mayer et al., 1999).
Studies of patients with lesions to the parietal lobe
have demonstrated that lesions to the angular gyrus tend to lead to greater impairments in memorized mathematical facts, such as multiplication table
s, with relatively unimpaired subtraction abilities. Conversely, patients with lesions in the region of the intraparietal sulcus
tend to have greater deficits in subtraction, with preserved multiplication abilities (Dehaene and Cohen, 1997). These double dissociations lend support to the idea that different regions of the parietal cortex are involved in different aspects of numerical processing.
Impairment
Impairment may refer to:* A medical condition that leads to disability* In accounting, a downward revaluation of fixed assets* In health, any loss or abnormality of physiological, psychological, or anatomical structure or function, whether permanent or temporary...
in which patients have difficulty performing simple mathematical tasks, such as adding, subtracting, multiplying and even simply stating which of two number
Number
A number is a mathematical object used to count and measure. In mathematics, the definition of number has been extended over the years to include such numbers as zero, negative numbers, rational numbers, irrational numbers, and complex numbers....
s is larger. Acalculia is distinguished from dyscalculia in that acalculia is acquired late in life due to neurological injury such as stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
, while dyscalculia is a specific developmental disorder
Specific developmental disorder
Specific developmental disorders categorizes specific learning disabilities and developmental disorders affecting coordination.-ICD-10 taxonomy:...
first observed during the acquisition of mathematical knowledge. The name comes from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
"a" meaning "not" and Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
"calculare", which means "to count".
Variations
Acalculia is associated with lesions of the parietal lobeParietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
(especially the angular gyrus
Angular gyrus
The angular gyrus is a region of the brain in the parietal lobe, that lies near the superior edge of the temporal lobe, and immediately posterior to the supramarginal gyrus; it is involved in a number of processes related to language, mathematics and cognition...
) and the frontal lobe
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
and can be an early sign of dementia
Dementia
Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...
. Acalculia is sometimes observed as a "pure" deficit, but is commonly observed as one of a constellation of symptoms, including agraphia, finger agnosia and left-right confusion, after damage to the left angular gyrus, known as Gerstmann's syndrome (Gerstmann, 1940; Mayer et al., 1999).
Studies of patients with lesions to the parietal lobe
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
have demonstrated that lesions to the angular gyrus tend to lead to greater impairments in memorized mathematical facts, such as multiplication table
Multiplication table
In mathematics, a multiplication table is a mathematical table used to define a multiplication operation for an algebraic system....
s, with relatively unimpaired subtraction abilities. Conversely, patients with lesions in the region of the intraparietal sulcus
Intraparietal sulcus
The intraparietal sulcus is located on the lateral surface of the parietal lobe, and consists of an oblique and a horizontal portion. The IPS contains a series of functionally distinct subregions that have been intensively investigated using both single cell neurophysiology in primates and human...
tend to have greater deficits in subtraction, with preserved multiplication abilities (Dehaene and Cohen, 1997). These double dissociations lend support to the idea that different regions of the parietal cortex are involved in different aspects of numerical processing.